Silicon-Based Electrolyte Additive for Lithium Battery SEI Stability
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Solution Overview
Problem
Lithium secondary batteries face issues with cycle life deterioration and swelling due to decomposition reactions of the electrolyte solution, especially when stored at high temperatures, leading to increased internal pressure and performance problems.
Innovation Solution
A non-aqueous electrolyte solution for lithium secondary batteries is developed, comprising a lithium salt, a carbonate-based organic solvent, and a silicon-based compound with a specific chemical formula that suppresses decomposition reactions by forming a stable Solid-Electrolyte Interface (SEI) film, enhancing cycle life and preventing swelling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a carbonate-based organic solvent is used in the electrolyte solution, then lithium ion conductivity is improved, but decomposition reactions occur at high temperatures causing gas generation and battery swelling
Solution Approach 1:
A silicon-based compound is introduced as an intermediary substance that reacts preferentially with lithium ions to form a stable SEI film. This intermediary layer acts as a protective barrier between the electrolyte solution and the anode, preventing direct decomposition reactions of the carbonate-based solvent while maintaining lithium ion conductivity. The silicon-based compound thus mediates the interaction between the electrolyte and electrode, eliminating harmful gas generation.
Solution Approach 2:
The chemical composition and structure of the SEI film are changed by introducing silicon-based compounds with specific molecular structures (containing Si-O-Si or Si-O-C bonds). This parameter change in the SEI film composition enhances its thermal stability and chemical inertness at high temperatures, preventing the decomposition reactions that lead to gas generation while preserving the necessary ionic conductivity for battery operation.
2Stability of the object's composition
If the SEI film is formed to prevent anode decomposition, then electrochemical stability is improved, but the SEI film breaks down at high temperatures causing continuous side reactions
Solution Approach 1:
The SEI film is transformed from a simple organic compound layer to a composite structure containing silicon-based compounds with Si-O-Si or Si-O-C bonds. This composite material structure combines the benefits of organic SEI films (ion conductivity) with the thermal and chemical stability of silicon-based networks. The resulting composite SEI film maintains structural integrity at high temperatures, preventing breakdown and continuous side reactions.
Solution Approach 2:
The silicon-based compound reacts during initial battery cycles to form a pre-stabilized SEI film with enhanced thermal and chemical stability. This preliminary formation of a robust SEI structure prevents subsequent breakdown and continuous decomposition reactions that would otherwise occur at high temperatures, ensuring long-term reliability.
3Reliability
If additives are added to change SEI film formation reactions, then some battery characteristics are improved, but other characteristics are deteriorated
Solution Approach 1:
Instead of uniformly modifying the entire electrolyte composition with multiple additives, the invention introduces a specific silicon-based compound that locally modifies the SEI film formation process at the anode interface. This localized action achieves the desired stabilization effect precisely where needed (at the electrode surface) without requiring complex bulk electrolyte modifications, thus improving reliability while minimizing complexity increase.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution improves the cycle life characteristics and prevents swelling phenomena by stabilizing the SEI film, maintaining lithium ion reversibility, and reducing internal pressure, thus enhancing battery performance at high temperatures.
Implementation Method 1
A non-aqueous electrolyte solution for lithium secondary batteries is developed, comprising a lithium salt, a carbonate-based organic solvent, and a silicon-based compound with a specific chemical formula that suppresses decomposition reactions by forming a stable Solid-Electrolyte Interface (SEI) film
Implementation Method 2
lithium ions emitted from a cathode active material such as lithium metal oxide transfer to an anode active material such as graphite, and intercalate into layers of the anode active material
Implementation Method 3
The SEI film acts as an ion tunnel, and enables only lithium ions to pass therethrough
Implementation Method 4
a non-aqueous electrolyte solution having a proper amount of lithium salt dissolved in a mixed organic solvent
Data Source
AI summary
Disclosed are a non-aqueous electrolyte solution for a lithium secondary battery and a lithium secondary battery comprising the same. The non-aqueous electrolyte solution for a lithium secondary battery comprises a silicon-based compound represented by a specific chemical formula and having both a hydroxyl group and a hydrocarbon group having a carbon-carbon double bond. When it is applied to a lithium secondary battery, the non-aqueous electrolyte solution improves deterioration of cycle life characteristics occurring after repeated charge/discharge cycles and prevents swelling phenomena by suppressing a decomposition reaction of an electrolyte solution even when a battery in a fully charged state is stored at high temperature or is charged/discharged, thereby enhancing the life characteristics at high temperature.